The protection of digital content transferred between computers over a network and transferred from a computer or other host device or a server to an associated playback device is important for many organizations. The DRM process often involves encrypting the pieces of content (e.g., encrypting the binary form of the content) to restrict usage to those who have been granted a right to the content, which is typically pieces of music or video programs.
Cryptography is the traditional protection method, but for many digital file transfer situations, a party that legitimately receives the content might try to break the DRM protection scheme, so as to give illicit access to third parties. Hence an identified weak link in the DRM security is in the overall process, rather than the encryption scheme. For instance, one of the more successful DRM schemes distributes music and video content via the Internet. The DRM system distributes to a user's computer content that has been encrypted. The user's computer then decrypts the received content, generates local keys for encrypting the content, and uses the local keys to re-encrypt the content. Typically the content in encrypted form may also be downloaded, via a local connection such as a USB (universal serial bus) connection, to an associated playback-only device such as an audio or video media player, which similarly decrypts and re-encrypts the content before playing same.
The present inventors have identified a potential security issue with this approach. There is a need to strengthen the security linking a particular playback device to the associated host device (computer) and also to the central server from which the content and/or DRM information is downloaded.